Embodiments of the present invention relate to optical frequency combs, and more specifically, to generation of optical frequency combs using microring resonators.
Optical frequency combs, with the broad optical bandwidth of ultrafast lasers and the optical-radio frequency (RF) clockwork, enable precision spectroscopy, frequency metrology, and astrophysical spectrography. Ultrafast pump-probe experiments, exploiting the ultrafast pulse durations, have made tremendous progress in electronic/molecular dynamics. Ultimately, a combination of frequency comb and temporal pulse-shaping technologies enables generation of arbitrary optical waveforms with applications in communications and coherent control of ultrafast chemistry.
Continuous-wave (cw) pumped monolithic microresonators serve as an alternative platform for comb generation through broadband four-wave mixing (FWM). With anomalous group-velocity-dispersion (GVD) and self-phase modulation (SPM), optical solutions can be generated, demonstrating broad bandwidths and RF-optical stability. Obtaining anomalous GVD broadly across arbitrary center frequencies, however, is challenging for microresonators. Dispersion engineering by conformal coating and waveguide shaping are possible, but often lead to lower cavity optical quality factors (Qs).
Thus, there remains a need for microresonator-based optical frequency combs displaying normal dispersion.